Copying process

ABSTRACT

A photosensitive non-silver free radical film is placed in physical contact with copy material to be duplicated and on exposing the film to radiation from a powerful red light, either positive copy or negative copy is obtained.

United States Patent Fotland et al.

[ 51 Apr. 25, 1972 [54] COPYING PROCESS [72] Inventors: Richard A.Fotland, Lyndhurst; Virgil E.

Straughan, Euclid; John Cameron, Cleveland, all of Ohio HorizonsIncorporated, a Division of Horizons Research Incorporated 22 Filed:June11,1969

21 Appl.No.: 832,143

[73] Assignee:

[52] U.S. Cl ..96/48, 96/47, 96/90 [51] Int. Cl v.G03c 5/24, G030 11/00,G030 1/92 [58] Field of Search ..96/90, 48, 47

[56] References Cited UNITED STATES PATENTS 3,042,519 7/1962 Wainer..96/48 Fotland et al ..96/27 3,510,300 5/1970 3,194,659 7/1965 Baus etal. ...96/47 3,445,232 5/1969 Shirey et al. ..96/47 PrimaryExaminer-Norman G. Torchin Assistant Examiner-Richard E. FichterAnorneyLawrence 1. Field [57] ABSTRACT A photosensitive non-silver freeradical film is placed in physi' cal contact with copy material to beduplicated and on exposing the film to radiation from a powerful redlight, either positive copy or negative copy is obtained.

7 Claims, 2 Drawing Figures Patented A ril 25, 1972 I FIG.

FIG. ,2.

N NWA E H V NT FTO S A E D mm 6N W W ,mv

ATTORNEY COPYING PROCESS This invention relates to a completely dry,non-silver photographic process for obtaining either a positive or anegative full size copy of an original document, and a process capableof providing continuous-tone copies with control over the contrast ofthe copy.

More particularly, the invention relates to the use of free radicalphotosensitive formulations which are capable of being opticallydeveloped, the compositions being coated upon a transparent base orimbibed in a paper base in an ap paratus of the type hereinafterdescribed.

The invention will be more readily understood from the description whichfollows, taken with the drawings in which:

FIG. 1 is a schematic showing of a copying apparatus; and

FIG. 2 is a similar view of a modified apparatus.

The copying apparatus shown in FIG. 1 comprises a lamp 30, mountedwithin a reflector 32, positioned and shaped so as to reflect radiationfrom lamp 30 towards two glass filters. Filter 34 is a red glass filter,such as Corning No. 2,408, and filter 36 is a heat absorbing glassfilter, such as Corning Glass No. 2,600, or similar filter. Suitablemeans (not shown) are provided for supporting a copy sheet 16 and anoriginal 14 in physical contact with each other, the copy sheet beingpositioned between the lamp and the original to be copied. If copy sheet16 bears a photosensitive coating, this is positioned next to theoriginal 14.

FIG. 2 is a similar view of a copying apparatus in which means areprovided for moving material through the apparatus, intermittently orcontinuously.

The copying apparatus shown in FIG. 2 may include a housing in which theseveral moving parts of the apparatus are supported, including a maindrive roller 12 by means of which an original 14 and a photosensitivecopy sheet 16 are drawn through the apparatus, entering through anentrance 18 and exiting through an exit 20. Drive roller 12 is supportedin suitable bearings which may be supported in a frame or in bearingblocks (not shown) suitably mounted on the housing 10.

Means are provided in the apparatus for holding the original and thecopy sheet in intimate contact, this being an endless transparent belt22, trained around a plurality of idler rollers 24. Rollers 24 may beindependently rotatable or they may be connected to one another bysuitable gearing, and may be supported either in housing 10 or in aseparate frame. Any other suitable means may be used to hold the copysheet and the original in intimate contact as they pass through theapparatus.

The apparatus includes means for providing the radiation required forthe copying process, such means include a lamp 30, for example a lr KwGeneral Electric Quartzline (RTM) Lamp Type O l500T3/CL, having alighted length of at least the width of the copy sheet. Lamp 30 issupported in a reflector 32 having a generally elliptical configurationwhereby the radiation output of the lamp is directed toward the open endof reflector 32 and passes out of the reflector and through one or morefilters 34, 36.

The quality or spectral distribution of the radiation reaching the copysheet and original is determined by the spectral filters 34 and 36.Preferably filter 34 is a Corning red glass filter (Corning No. 2408)while filter 36 is a heat-absorbing glass filter (Corning Glass No.2600) having a long wavelength cutoff near 750 nanometers. Theheat-absorbing glass filter 36 is mounted on a mechanical linkage sothat it may be moved out of the radiation path in such a manner thatradiation falling on the original and copy sheet may be either filteredby the red glass filter alone or by both the red glass andheat-absorbing filters. An additional radiation source in the apparatusis provided by a white fluorescent lamp 38 mounted in its owncylindrical reflector housing 40.

The function of the fluorescent lamp 38 is to provide the photosensitivecopy sheet with a blanket exposure of radiation to which thephotosensitive film or paper is sensitive prior to the copying step;generally this radiation lies in the near UV and violet portions of thespectrum. The use of the fluorescent lamp 38 is optional since theblanket exposure may be provided by merely subjecting the copy sheet tonormal room illumination for a period of several seconds before it isdrawn into the apparatus housing through entrance 18.

Among the non-silver photosensitive compositions which may be employedin this copying process are the free-radical photosensitive compositionspatented by Eugene Wainer and his co-workers, including those describedin the following:

U.S. Patents The following specific examples are intended to demonstratethe application and utility of the copying process of this invention andare not intended to be construed as limiting the invention.

EXAMPLE I A photosensitive copy sheet was prepared under a red safelightby dissolving 400 mg of 4,4-vinylidene-bis-(N,N- dimethylaniline), 100mg of 2,6-di-tert-butyl-p-creso], 25 mg of Z-p-dimethylaminostyrylpyridine, and 400 mg of iodoform in a 10 percent solution ofpolycarbonate in methylene chloride. The solution was coated on a 5 milpolyester film base using a Bird applicator bar having a wet coatingthickness of 1.5 mils. The film was dried in an oven for two minutes atC. The coating procedure is fully described in Photographic Science andEngineering, Vol. 8, No. 2., pp. -l03 andVol. 5,p. 98 (1961).

This photosensitive material, as well as those described in theaforementioned patents, is capable of being optically developed. In thistechnique for increasing the sensitivity of the film, a faint initialexposure generates trace quantities of image dye which then selforauto-sensitize the photosensitive material to the red portions of thespectrum. If the film, subsequent to the initial exposure, is subjectedto a blanket exposure to red illumination, image intensification occursin exposed areas. It has been found that the rate of opticaldevelopment, i.e., the rate at which the density increases with timeduring optical development, is a sensitive function of film temperature.The rate of density increase for most films is such that an increase inthis rate of 2% times occurs for every 10 C rise in film temperature. Itis this thermal sensitivity of optical development which is employed inthe copying process to obtain a positive image. A significantimprovement over prior art thermographic processes resides in the degreeof control over the contrast of the positive copy which is provided byvirtue of the provision for blanket post-exposure of the film which, inturn, determines the temperature sensitivity and degree of opticaldevelopment required.

This control may best be understood from the following discussion. Ifthe image being copied is of low contrast, i.e., there exists a lowdensity difference between image and background areas, a high contrastcopy may be obtained by adjusting the intensity of the blanket exposurelamp 38 so that the level of exposure of the photosensitive layer is inthe region of 500 ft.-candle seconds as measured by a conventionalphotographic light meter. This low exposure level imposes a requirementfor a longer optical development time which involves a highersensitivity to thermal effects to thus provide a high contrast copy. Inthe apparatus shown in FIG. 2, a high contrast copy is obtained at apaper speed through the apparatus of 6 ft./min. High quality, highcontrast, continuoustone images may be copied in this manner.

A low contrast copy may be obtained by providing a high level blanketexposure together with a low degree of optical development. To realizethese conditions, the intensity of the fluorescent blanket exposure lamp38 is raised so that the photosensitive layer exposure is in the regionof 5,000 ft.-candle-seconds, and the speed of the apparatus is increasedso that the copying operation is carried out at a speed of 20 ft./min.Under these conditions, the copy has a lower contrast than the original.

In this process of obtaining a positive copy, the heat-absorbing glassfilter 36 must be removed from the radiation path so that the thermalradiation from the lamp selectively heats dark image areas on theoriginal. The thermal energy in image areas of the original istransferred to localized areas of the photosen-' sitive layer, thusincreasing the rate of optical development in image areas to provide apositive image.

A negative copy may be obtained employing the same photosensitivematerials and apparatus by slightly changing the copying conditions.Negative copies are obtained by a reflex copy technique during the redlight exposure. In this mode of operation, the heat-absorbing glassfilter 36 must be interposed in the radiation path to prevent theselective image heating which leads to a positive copy. Thephotosensitive copy sheet is subjected to the same blanket exposure andrun through the apparatus with the image to be copied and thephotosensitive layer in intimate contact. The rate of density buildupwith red light exposure is exponential. Because of the high dependenceof density upon red light exposure, reflex copies may be obtained since,in areas where the image being copied is white, the red light isreflected, thus almost doubling the red light exposure compared to imageareas or areas where the area being copied is black.

Contrast control may be effected in negative copying in much the samemanner as that realized for a positive copy. In order to realize a lowcontrast negative copy, a high level of initial blanket exposure fromlamp 38 is provided together with a low degree of optical development,i.e., a high machine speed. The converse conditions will result inobtaining a high contrast copy of the original.

In all of the above procedures, a final step is required to fix orrender the copy sheet light insensitive. This fixing operation iscarried out by subjecting the copy sheet to elevated temperatures whichserve to drive the volatile activator (iodoform in the above example)out of the film. For the photosensitive formulation described above,fixing is carried out at a temperature of 145 C for a period of 1minute.

Reflex copying is possible because of the extremely high contrastobtained in optical development, i.e., the image density varies quiterapidly with exposure. In black areas of the original, possibly only 5percent of the incident red light exposure is reflected. In white areasof the original, 80 percent of the red light is reflected. The ratio ofcopy sheet red light exposure between white areas and black areas isthus 1.8/1.05 or about 1.7: 1. This ratio is sufficient to provide adark image on the copy sheet corresponding to the highly reflectingregions on the original and no copy sheet darkening in low reflectivityareas.

The simplicity of switching from a negative to a positive is apparent.One constraint is present in forming a positive image that is notpresent in forming a negative image. This is the requirement for aminimum power level (about 1 watt/cm minimum total power at the copysheet) required to generate a differential temperature between the dark(heat absorbing) areas and white areas on the original. At lower powerlevels, the differential heating is reduced due to lateral heatconduction in the original. The positive mode works because of the veryhigh temperature coefficient of optical development rate. The rate ofoptical development goes up a factor of 2.5 for every C increase intemperature. Thus, development occurs much faster in hot areas (areas ofthe copy sheet in contact with a dark area on the original) than incooler areas.

Summarizing, the present invention is directed to reflex copyingprocesses utilizing free radical non silver photosensitive films, inwind! exposing radiation strikes a copy sheet while the copy sheet is inphysical contact with an original (to be copied), the exposing radiationstriking the copy sheet before it strikes the original. Either anegative or a positive image may be produced, as described above.

What is claimed is:

l. A method of producing positive copies of a document which comprises:

1. exposing a copy sheet containing a free radical, non

silver, photosensitive composition capable of being optically developedto uniform blanket radiation in near U.V., violet or blue wavelengths(3,500 A to 4,500 A) sufficient to sensitize the composition tosubsequent exposure to visible radiation in the red;

2. bringing the sensitized copy sheet into physical contact with thedocument to be reproduced;

. projecting red and infrared radiation onto said copy sheet in a mannersuch that the radiation passes through at least one optical filter whichtransmits only in the red and infrared portions of the spectrum beforesaid radiation strikes the copy sheet and wherein said radiation strikesthe copy sheet before it passes to the document to be reproduced, theamount of radiation projected being sufficient to produce an image onsaid copy sheet; and

4. thereafter fixing the resulting image in the copy sheet by heatingthe sheet to a temperature of about C for a short interval.

2. The process of claim 1 wherein a high contrast positive copy isobtained by adjusting the blanket exposure of step l to a relatively lowlevel and providing a relatively high level of red and infraredradiation for optical development.

3. The process of claim 1 wherein a low contrast positive copy isobtained by adjusting the blanket exposure of step l) to a relativelyhigh level and providing a relatively low level of red and infraredradiation for optical development.

4. A method of producing negative copies of an original document whichcomprises:

1. exposing a copy sheet containing a free radical non-silver,photosensitive composition capable of being optically developed touniform blanket radiation in near U.V., violet or blue wavelengths(3,500 A to 4,500 A) sufficient to sensitize the composition tosubsequent exposure to visible radiation in the red;

2. bringing the sensitized copy sheet into physical contact with theoriginal document to be reproduced;

. projecting red radiation onto said copy sheet in a manner such thatthe radiation passes through a heat-absorbing filter and at least oneoptical filter transmitting only in the red portion of the spectrumbefore it strikes the copy sheet and wherein said radiation strikes thecopy sheet before it passes to the document to be reproduced, the amountof radiation projected being sufficient to produce an image on said copysheet; and

4. thereafter fixing the resulting image in the copy sheet by heatingthe sheet to a temperature of about 145 C for a short interval.

5. The process of claim 4 wherein a high contrast negative copy isobtained by adjusting the blanket exposure of step (I) to a relativelyhigh level and providing a relatively low level of radiation for opticaldevelopment.

6, The process of claim 4 wherein a low contrast negative copy isobtained by adjusting the blanket exposure of step (I) to a relativelylow level and providing a relatively high level of radiation for opticaldevelopment.

7. The process of claim 4 wherein the free radical film is a coating onone surface of the copy sheet, and that surface is the one in physicalcontact with the material to be reproduced.

2. bringing the sensitized copy sheet into physical contact with thedocument to be reproduced;
 2. The process of claim 1 wherein a highcontrast positive copy is obtained by adjusting the blanket exposure ofstep (1) to a relatively low level and providing a relatively high levelof red and infrared radiation for optical development.
 2. bringing thesensitized copy sheet into physiCal contact with the original documentto be reproduced;
 3. projecting red radiation onto said copy sheet in amanner such that the radiation passes through a heat-absorbing filterand at least one optical filter transmitting only in the red portion ofthe spectrum before it strikes the copy sheet and wherein said radiationstrikes the copy sheet before it passes to the document to bereproduced, the amount of radiation projected being sufficient toproduce an image on said copy sheet; and
 3. The process of claim 1wherein a low contrast positive copy is obtained by adjusting theblanket exposure of step (1) to a relatively high level and providing arelatively low level of red and infrared radiation for opticaldevelopment.
 3. projecting red and infrared radiation onto said copysheet in a manner such that the radiation passes through at least oneoptical filter which transmits only in the red and infrared portions ofthe spectrum before said radiation strikes the copy sheet and whereinsaid radiation strikes the copy sheet before it passes to the documentto be reproduced, the amount of radiation projected being sufficient toproduce an image on said copy sheet; and
 4. thereafter fixing theresulting image in the copy sheet by heating the sheet to a temperatureof about 145* C for a short interval.
 4. A method of producing negativecopies of an original document which comprises:
 4. thereafter fixing theresulting image in the copy sheet by heating the sheet to a temperatureof about 145* C for a short interval.
 5. The process of claim 4 whereina high contrast negative copy is obtained by adjusting the blanketexposure of step (1) to a relatively high level and providing arelatively low level of radiation for optical development.
 6. Theprocess of claim 4 wherein a low contrast negative copy is obtained byadjusting the blanket exposure of step (1) to a relatively low level andproviding a relatively high level of radiation for optical development.7. The process of claim 4 wherein the free radical film is a coating onone surface of the copy sheet, and that surface is the one in physicalcontact with the material to be reproduced.